Also all in favour of thin phones here, but once you need to walk around carrying an extra - external - battery, or need to hop from coffeeshop to coffeeshop, hoping for a free power socket, something went wrong... The iPhone is advertised as a do-all device (which it effectively is), but it just starts lacking the power to run all these wonderful applications. True, maybe not for very light users who don't install extra apps, but if you're e.g. on a city trip abroad, using a dictionary app, maps, the camera, reading some museum brochures you downloaded, ... it won't last a day - by far not. And then you wonder if you should include the thickness of the extra battery you're carrying to the actual size of the phone. Or if maybe making the phone a few millimeters thicker would make sense.